1. Field of the Invention
The present invention relates to a heating cooking device and a heating cooking method using superheated vapor, and especially to a heating cooking device realizing a high temperature uniformity.
The present application claims the benefit of priority based upon Japanese Patent Application No. 2015-137114 filed on Jul. 8, 2015, the entirety of which is incorporated herein by reference.
2. Description of the Related Art
Superheated vapor is vapor obtained by heating water vapor to a temperature exceeding 100° C. at a constant pressure. Unlike water vapor or high-pressure, high-temperature water vapor, the superheated water vapor (or superheated vapor) is heat-radiating gas that radiates far infrared rays preferable for heating food, and has an advantage that, for example, oxygen is blocked and thus and oxidation is prevented in an atmosphere thereof. It is considered that use of superheated vapor allows meat, fish or the like to be baked to provide good taste (see, for example, Japanese Laid-Open Patent Publication No. 2001-190410).
A known device that bakes food such as meat, fish or the like by use of superheated vapor is, for example, a device shown in FIG. 8 in Japanese Laid-Open Patent Publication No. 2001-190410. This device includes a boiler (not shown), a superheated vapor generation device “a” that is connected with the boiler with a pipe “d” and has an ejection opening “b”, and a conveyor “c” on which food may be placed to be transported. This device is operated as follows. Water vapor is generated from the boiler and is transported to a heating pipe a1 provided in the superheated vapor generation device “a” via the pipe d. The water vapor flowing in the heating pipe a1 is heated by a burner a2 provided in the superheated vapor generation device “a” to generate superheated vapor. The superheated vapor is ejected from the ejection opening “b” and blown onto food placed on the conveyer “c”. Thus, the food is baked.
According to a common method of generating superheated vapor, water vapor is combusted by a burner by use of fuel such as gas, petroleum or the like as described above. However, such a system using a burner requires very large scale facilities including smoke discharge facilities, which needs an increased investment for the facilities. Such a system also requires additional facilities against environmental pollution or the like. In addition, the energy efficiency at which superheated vapor is generated is not very high although this is not noticed much because this system is commonly used. There is another system using an electromagnetic induction-type heating unit. The energy efficiency of this system is not very high, either.
An example of system using an electromagnetic induction-type heating unit is described in Japanese Laid-Open Patent Publication No. 2002-83673. In the case of using an electromagnetic induction coil, even a small device requires power of about 90 kW (kilowatts). Considering that a large scale refrigerator for industrial use requires about 75 kW at most, the power required by the system using an electromagnetic induction coil is outrageously large. There is also a superheated vapor cooking device for home use that has substantially the same size as that of a microwave oven. With such a device, water is boiled each time to generate water vapor, and superheated vapor is generated from the water vapor. Since the time to generate water vapor is necessary, the device is not convenient to be used. Each time the device becomes out of the water for generating water vapor, supplement of water is necessary. For these reasons, it is difficult to use this device continuously for industrial use. The amount of superheated vapor assumed to be generated by a device for home use is significantly different from the amount assumed to be generated by a device for industrial use. Therefore, in the case where a device developed for home use is subjected to industrial use, the amount of heat is not sufficient, and heating is not performed sufficiently.
In such a situation, the present inventor developed a heating cooking device using superheated vapor and disclosed the device in Japanese Patent No. 4427090. The heating cooking device disclosed in Japanese Patent No. 4427090 uses superheated vapor to perform heating in a plurality of temperature ranges (multi-purpose heating cooking device). The heating cooking device includes a superheated vapor generation device connected with a hot vapor generation device and a heating pot into which the superheated vapor is introduced. In this heating cooking device, a part of the superheated vapor generation device that heats hot vapor generated by the hot vapor generation device to generate superheated vapor is located inside the heating pot. A first cooking container in communication with the inside of the heating pot is attached to a part of the heating pot.
This heating cooking device includes the superheated vapor generation device that heats hot vapor from the hot vapor generation device to generate superheated vapor, and the heating pot into which the superheated vapor is introduced. The first cooking container in communication with the inside of the heating pot is attached to a part of the heating pot. Therefore, the heating cooking device performs heating in a plurality of temperature ranges by use of superheated vapor continuously generated, with no use of a burner. In the case where cooking is performed with use of superheated vapor generated from boiler vapor, a boiler is needed. However, the heating cooking device described in Japanese Patent No. 4427090 does not need such a boiler. Cooking by use of superheated vapor is realized as long as there is a power supply. Therefore, this heating cooking device is suppressed from being increased in the scale and is compact.
For further improving the heating cooking device described in Japanese Patent No. 4427090, the present inventor paid attention to the following points. The heating cooking device described in Japanese Patent No. 4427090 is configured to heat food in a splendid manner by use of superheated vapor and also to perform heating in a plurality of temperature ranges by use of exhaust heat. A heating cooking device is required to provided convenience that the heating is performed in a plurality of temperature ranges and is also required to have uniformity in the temperature in the heating pot (in the furnace) in a single temperature range. This will be described in more detail. A superheated vapor cooking device having substantially the same size as that of a microwave oven is for home use, and the number of dishes that are put therein is one or two. Therefore, the user does not pay attention to a temperature non-uniformity in the furnace, and the non-uniformity in the heating or taste is not a serious problem because the heating cooking device is for home use. By contrast, in the case where a heating cooking device is used continuously at an industrial level, a great number of food materials are put into one heating pot (heating furnace) and heated at the same time. Therefore, a non-uniformity in the temperature leads to non-uniformity in the heating or taste. When this occurs, the cooked materials may not be provided for the market. In addition, the heating cooking device is used many times each day. For these reasons, a non-uniformity in the heating or taste caused by the non-uniformity in the temperature cannot be ignored.
The heating cooking device described in Japanese Patent No. 4427090 heats the food materials in the heating pot by use of superheated vapor generated by heating hot vapor having a pressure of about 1 atm. Therefore, as compared with a case using superheated vapor derived from boiler vapor having a high pressure, a high temperature and a high flow rate, the temperature uniformity in the furnace of the heating cooking device described in Japanese Patent No. 4427090 is significantly higher. However, a heating cooking device having a temperature uniformity exceeding that of the heating cooking device described in Japanese Patent No. 4427090 may be desired. The present inventor accumulated further studies to complete a heating cooking device having a temperature uniformity exceeding that of the conventional heating cooking device and thus arrived at the present invention.
The present invention made in light of the above-described point has a main object of providing a heating cooking device and a heating cooking method realizing a high temperature uniformity.